US2355021A - Washing apparatus for air preheaters - Google Patents

Description

Aug. 1, 1944. J. wArrKus WASHING APPARATUS FOR AIR PREHEATERS Filed Aug. 8, 1941 Aime 41 7161504 g. ATTORNEY Patented Aug. 1, 1944 WASHING APPARATUS FOR Am 7 PREHEATERS Joseph Waitkus, Wellsville, N. Y., assigno'r to The Air Preheater Corporation, New York, N. Y.

Application August 8, 1941, Serial No. 405,939 6 Claims. (01. 257-1) The present invention relates to heat transfer apparatus and particularly to improvements in apparatus for washing the heat transfer surfaces of rotary, regenerative, air preheaters, such as Ljungstrom preheaters; 1

In the Liungstrom air preheater metallic heat transfer plates carried in compartments of a rotor absorb heat in passing through the gas side of the preheater and subsequently they are turned into position to yield their heat to air flowing through the air side of the preheater. Soot and ashes are deposited on the surfaces of the heat transfer plates from the gases flowing thereover.

Soot blowers are ordinarily provided for remov-' ing these deposits. However, experience has indicated that the deposits are heaviest at points near the innermost portions and also in the outer parts of the compartments because the soot blower does not clean these surfaces as effectively'as it cleans the plates which are in the center portion of the variouscompartments of the rotor.

' The present invention contemplates apparatus for cleaning the heat transfer surfaces in the rotor compartments bycontinuously directing a stream of water thereover. This is eifected by means of a nozzle rotating in a circular path above the rotor in the same direction as the latter on the air side of the preheater. Near the center and also near the outer edge of the rotor the path of the nozzle is tangential to the path of movement of the heat transfer elements in these parts of the rotor: compartments. Hence, larger quantities of water flow over these elements be-' cause of the fact that the movement of the nozzle relatively to the movement of the elementsis slowest at'the'se points.

The invention will be best understood upon consideration of the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawing in which T Figure 1 is a plan view preheater provided with washing apparatus in accordance with the present invention, some parts being shown in section;

Figure 2 is a sectional view on the line 22 in Figure 1; and

Figures 3 and 4 are sectional views of an alternative detail of construction.

In the drawing the numeral l designates the casing of a Ljungstrom air preheater having a rotor l2 subdivided by radial partitions I4 to form a number of sector-shaped compartments each of which contains a plurality of heat transof a Ljungstrom air fer elements 16 in the form of undulated metallic plates. The rotor is turned slowly clockwise, for

example, aboutza vertical axis by a motor 20' geared by a speed'reducer 22 to the'rotor shaft 24 so that the heat transfer elements are turned slowly to first absorb heat from hot gases pass.- ing to the outlet duct 26 at the gas side of the air preheater and when rotor movement positions them in the air side of the preheater the heat transfer elements yield their heat to air entering the preheater through the air inlet duct 28'.

In accordance with the present invention the preheater is provided preferably on the air side with. a nozzle 30 rotatable in a circular path above the rotor [2. As shown, the nozzle is at the end-of a right angled extension 32 of a pipe 34 mounted for rotation clockwise, for example, about a vertical axis-substantially in the center of the air duct. The diameter of the circle of rotation of the nozzle-is preferably nearly equal to the radial depth of the sector compartments in which the heat transfer'plates are mounted so that all may be washed. The pipe 34 is guided for rotation in a bearing 36 on a housing 38 suitably attached to'the air duct wall or'the framework of the preheater. Intermeshing bevel 7 gears 40, 42 on the-pipe-34 and a shaft 44 driven throughsuitable reduction gearing by a motor 46 provide a means by which the pipe 34- maybe rotated and the nozzle 30 swung slowly in a circular path. Water issupplied to the nozzle pipe Preferably, the motor 46 operates whenever the preheater is inuse and water is continuously supplied to the nozzle 30. As the latter is moved clockwise, for example, in a circular path above the heat transfer plates passing therebeneath, the particles of soot, ash-and other deposits are removed from the heat transfer elements by the stream of water flowing thereover. Inasmuch as the clockwise movement of the nozzle is tangentialto the path; ofclockwise movement of the elements when the nozzle is near the outer ends of the compartments, the rate of relative movement between the nozzle and plates is lowest due to their moving in the same direction and a relatively greater amount of water flows over the heat transfer elements in the outer parts of the compartments than over elements located nearer to the center of the rotor. The speed of the rotor may also be slowed down, if desired, to decrease the rate of relative movement and thereby increase the effectiveness of the washing.

elements at the upper left hand portion of the rotor in Fig. 1 might, if wetted, carry water into the gas side of the preheater. One means of meeting 1 this condition is diagrammatically illustrated in Figs. 3 and 4. In these figures the nozzle pipe 34a and the coupling member 50a are arranged like a plug valve. Part of the wall of the pipe 34a is cut away near its upper end to receive water from the chamber in the coupling member 50a. When the port 501) leading from the chamber and coupling member 50a is obscured by the uncut portion of the wall of the pipe 34a the flow of washing fluid to the nozzle 30 is cut off. By properly proportioning and locating the port and the uncutportion of the wall of the pipe 34a the flow of fluid to the nozzles 30 may be automatically cut off over the desired arc in the circle of rotation'of the nozzle pipe 30.

What I claim is:

1. In a regenerative 'air preheater having a rotor divided into compartments carrying heat transfer surfaces for absorbing heat from hot gases flowing through a gas duct and imparting it to air flowing through an 'air duct; a nozzle supplied with a fluid for cleaning said heat transfer surfaces; means for supporting said nozzle for movement with respect'to said rotor in a circular path centered approximately in the middle of one of said ducts, said path having a radius approximately one-half the radial depth of the rotor compartments; and means for slowly rotating said nozzle and rotor in the same direction.

2.'In a regenerative air preheater having a horizontally disposed rotor divided into compartments carrying heat transfer plates for absorbing heat from gases flowing through a gas duct and impart it to air flowing through an air duct; a nozzle supplied with fluid for cleaning said plates; means for supporting said nozzle for movement above said rotor in a circular path cen tered approximately in the middle of one of said ducts, said path having a radius approximately one-half the radial depth of the rotor compartments; and means for slowly rotating said nozzle and rotor in the same direction 3. In a regenerative air preheater having a horizontal rotor divided into compartments carrying heat transfer plates for absorbing heat from hot gases flowing through a gas duct and imparting it to air flowing through an air duct; a rotatable arm positioned on the air duct above said rotor; a nozzle carried by said arm; means for supplying a cleaning liquid to said nozzle; means for supporting said arm for movement about a center substantially coincident with that of one of said ducts for swinging said nozzle in a circular path with respect to the rotor portion in said duct, said path having a diameter substantially equal to the radial depth of the rotor compartments; and means for slowly rotating said arm in the same direction as said rotor.

4. In a regenerative air preheater having a rotor divided into compartments carrying heat transfer surfaces for absorbing heat from hot gases flowing through a gas duct and imparting it to air flowing through an air duct; a nozzle supplied with a fluid for cleaning said heat transfer surfaces; means for supporting said nozzle for movement with respect to said rotor in a circular path centered approximately in the middle of one of said ducts, said path having a radius approximately one-half the radial depth of the rotor compartments; means for slowly rotating said nozzle and rotor in the same direction; and means controlled by the position of said nozzle for automatically discontinuing the supply of fluid to said nozzle as it moves, through a predetermined portion of its path.

5. In a regenerative air preheater having a horizontally disposed rotor divided into compartments carrying heat transfer surfaces for ab-' sorbing heat from gases flowing through its gas duct and impart it to air flowing through its air duct; a rotatable arm of a length approximating half the radial depth of the rotor compartments; a nozzle carried at one end of said arm; means for supplying a cleaning fluid to said nozzle; means for supporting said arm at its other end for movement about a center substantially coincident with that of the air ducts for swinging said nozzle in a circular path above the part of the rotor passing through said duct, said path having a diameter substantially equal to the radial depth of the rotor compartments; and means for slowly rotating said arm and rotor in the same direction.

6. In a regenerative air' preheater having a horizontally disposed rotor divided into com partments carrying heat transfer surfaces for absorbing heat from gases flowing through its gas duct and impart it to air flowing through its air duct; a rotatable arm of a length approximating half the radial depth of the rotor compartments; a nozzle carried at one end of said arm; means for supplying a cleaning fluid to said nozzle; means for supporting saidarm at its other end for movement about a center substantially coincident with that of the air ducts for swinging said nozzle in r a circular path above the part of the rotor passing through said duct, said path having a diameter substantially equal to the radial depth of the rotor compartments; means for slowly rotating said arm and rotor in the same direction; and means controlled by the position of said nozzle for discontinuing the supply of water to said nozzle as it moves through a predetermined portion of its path.

JOSEPH WAITKUS.

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